Stephane Eranian b5b1eed6b8 perf core: Fix perf_proc_update_handler() bug ... [ Upstream commit 1a51c5da5a ] The perf_proc_update_handler() handles /proc/sys/kernel/perf_event_max_sample_rate syctl variable. When the PMU IRQ handler timing monitoring is disabled, i.e, when /proc/sys/kernel/perf_cpu_time_max_percent is equal to 0 or 100, then no modification to sysctl_perf_event_sample_rate is allowed to prevent possible hang from wrong values. The problem is that the test to prevent modification is made after the sysctl variable is modified in perf_proc_update_handler(). You get an error: $ echo 10001 >/proc/sys/kernel/perf_event_max_sample_rate echo: write error: invalid argument But the value is still modified causing all sorts of inconsistencies: $ cat /proc/sys/kernel/perf_event_max_sample_rate 10001 This patch fixes the problem by moving the parsing of the value after the test. Committer testing: # echo 100 > /proc/sys/kernel/perf_cpu_time_max_percent # echo 10001 > /proc/sys/kernel/perf_event_max_sample_rate -bash: echo: write error: Invalid argument # cat /proc/sys/kernel/perf_event_max_sample_rate 10001 # Signed-off-by: Stephane Eranian <eranian@google.com> Reviewed-by: Andi Kleen <ak@linux.intel.com> Reviewed-by: Jiri Olsa <jolsa@kernel.org> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Kan Liang <kan.liang@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1547169436-6266-1-git-send-email-eranian@google.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org>		2019-03-13 14:04:00 -07:00
..
callchain.c	treewide: convert ISO_8859-1 text comments to utf-8	2018-08-23 18:48:43 -07:00
core.c	perf core: Fix perf_proc_update_handler() bug	2019-03-13 14:04:00 -07:00
hw_breakpoint.c	perf/hw_breakpoint: Enable breakpoint in modify_user_hw_breakpoint	2018-08-30 14:49:23 -03:00
internal.h	perf: Make perf_callchain function static	2018-01-08 12:33:01 -03:00
Makefile	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
ring_buffer.c	perf/core: Fix impossible ring-buffer sizes warning	2019-02-20 10:29:09 +01:00
uprobes.c	This is a single commit that fixes a bug in uprobes SDT code	2018-12-06 10:35:19 -08:00